<!DOCTYPE html>

<head>
    <meta charset="utf-8">
    <title>菜鸟教程(runoob.com)</title>
</head>

<body>
    <div style="height:1px;overflow:hidden;background:red"></div>

</body>
<script>
    let test1 = document.getElementsByTagName();
    console.log(test1);

</script>

</html>